<?php  if (!defined('BASEPATH')) exit('No direct script access allowed');
/*
Load the plugin using:
	$this->load->plugin('captcha');
    $vals = array(
                    'word'         => 'Random word',
                    'img_path'     => './captcha/',
                    'img_url'     => 'http://www.your-site.com/captcha/',
                    'font_path'     => './system/texb.ttf',
                    'img_width'     => '150',
                    'img_height' => 30,
                    'expiration' => 7200
                );

    $cap = create_captcha($vals);
    echo $cap['image'];

The create_captcha() function returns an associative array with this data:

  [array]
  (
    'image' => IMAGE TAG
    'time'    => TIMESTAMP (in microtime)
    'word'    => CAPTCHA WORD
  )

The "image" is the actual image tag:
<img src="http://your-site.com/captcha/12345.jpg" width="140" height="50" />

The "time" is the micro timestamp used as the image name without the file
extension.  It will be a number like this:  1139612155.3422

The "word" is the word that appears in the captcha image, which if not
supplied to the function, will be a random string.

Here is a table prototype:

    CREATE TABLE captcha (
     captcha_id bigint(13) unsigned NOT NULL auto_increment,
     captcha_time int(10) unsigned NOT NULL,
     ip_address varchar(16) default '0' NOT NULL,
     word varchar(20) NOT NULL,
     PRIMARY KEY (captcha_id),
     KEY (word)
    )


Here is an example of usage with a DB.

On the page where the captcha will be shown you'll have something like this:

    $this->load->plugin('captcha');
    $vals = array(
                    'img_path'     => './captcha/',
                    'img_url'     => 'http://www.your-site.com/captcha/'
                );

    $cap = create_captcha($vals);

    $data = array(
                    'captcha_id'    => '',
                    'captcha_time'    => $cap['time'],
                    'ip_address'    => $this->input->ip_address(),
                    'word'            => $cap['word']
                );

    $query = $this->db->insert_string('captcha', $data);
    $this->db->query($query);

    echo 'Submit the word you see below:';
    echo $cap['image'];
    echo '<input type="text" name="captcha" value="" />';


Then, on the page that accepts the submission you'll have something like this:

    // First, delete old captchas
    $expiration = time()-7200; // Two hour limit
    $DB->query("DELETE FROM captcha WHERE captcha_time < ".$expiration);

    // Then see if a captcha exists:
    $sql = "SELECT COUNT(*) AS count FROM captcha WHERE word = ? AND ip_address = ? AND date > ?";
    $binds = array($_POST['captcha'], $this->input->ip_address(), $expiration);
    $query = $this->db->query($sql, $binds);
    $row = $query->row();

    if ($row->count == 0)
    {
        echo "You must submit the word that appears in the image";
    }

*/

class captcha {
	function create_captcha($data = '', $img_path = '', $img_url = '', $font_path = '')
	{
		$defaults = array('word' => '', 'img_path' => '', 'img_url' => '', 'img_width' => '100', 'img_height' => '30', 'font_path' => '', 'expiration' => 7200);
	
		foreach ($defaults as $key => $val)
		{
			if ( ! is_array($data))
			{
				if ( ! isset($$key) OR $$key == '')
				{
					$$key = $val;
				}
			}
			else
			{
				$$key = ( ! isset($data[$key])) ? $val : $data[$key];
			}
		}
		if ($img_path == '' OR $img_url == '')
		{
			return FALSE;
		}
		if ( ! @is_dir($img_path))
		{
			return FALSE;
		}
		if ( ! is_writable($img_path))
		{
			return FALSE;
		}
		if ( ! extension_loaded('gd'))
		{
			return FALSE;
		}
		list($usec, $sec) = explode(" ", microtime());
		$now = ((float)$usec + (float)$sec);
		$current_dir = @opendir($img_path);
		while($filename = @readdir($current_dir))
		{
			if ($filename != "." and $filename != ".." and $filename != "index.html")
			{
				$name = str_replace(".jpg", "", $filename);
	
				if (($name + $expiration) < $now)
				{
					@unlink($img_path.$filename);
				}
			}
		}
		@closedir($current_dir);
	   if ($word == '')
	   {
			$pool = '0123456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKLMNPQRSTUVWXYZ';
			$str = '';
			for ($i = 0; $i < 8; $i++)
			{
				$str .= substr($pool, mt_rand(0, strlen($pool) -1), 1);
			}
			$word = $str;
	   }
		$length    = strlen($word);
		$angle    = ($length >= 6) ? rand(-($length-6), ($length-6)) : 0;
		$x_axis    = rand(6, (360/$length)-16);
		$y_axis = ($angle >= 0 ) ? rand($img_height, $img_width) : rand(6, $img_height);
		$im = ImageCreate($img_width, $img_height);
		$bg_color        = ImageColorAllocate($im, 255, 255, 255);
		$border_color    = ImageColorAllocate($im, 153, 102, 102);
		$text_color        = ImageColorAllocate($im, 110, 110, 110);
		$grid_color        = imagecolorallocate($im, 255, 182, 182);
		$shadow_color    = imagecolorallocate($im, 255, 240, 240);
		/*$bg_color        = ImageColorAllocate($im, 255, 255, 255);
		$border_color    = ImageColorAllocate($im, 153, 102, 102);
		$text_color        = ImageColorAllocate($im, 204, 153, 153);
		$grid_color        = imagecolorallocate($im, 255, 182, 182);
		$shadow_color    = imagecolorallocate($im, 255, 240, 240);
		*/
		ImageFilledRectangle($im, 0, 0, $img_width, $img_height, $bg_color);
		$theta = 1;
		$thetac = 7;
		$radius = 16;
		$circles = 20;
		$points = 32;
		for ($i = 0; $i < ($circles * $points) - 1; $i++)
		{
			$theta = $theta + $thetac;
			$rad = $radius * ($i / $points );
			$x = ($rad * cos($theta)) + $x_axis;
			$y = ($rad * sin($theta)) + $y_axis;
			$theta = $theta + $thetac;
			$rad1 = $radius * (($i + 1) / $points);
			$x1 = ($rad1 * cos($theta)) + $x_axis;
			$y1 = ($rad1 * sin($theta )) + $y_axis;
			imageline($im, $x, $y, $x1, $y1, $grid_color);
			$theta = $theta - $thetac;
		}
		$use_font = ($font_path != '' AND file_exists($font_path) AND function_exists('imagettftext')) ? TRUE : FALSE;
		if ($use_font == FALSE)
		{
			$font_size = 12;
			$x = rand(0, $img_width/($length/3));
			$y = 0;
			echo "NO";
		}
		else
		{
			$font_size    = 16;
			$x = rand(0, $img_width/($length/1.5));
			$y = $font_size+2;
		}
	
		for ($i = 0; $i < strlen($word); $i++)
		{
			if ($use_font == FALSE)
			{
				$y = rand(0 , $img_height/2);
				imagestring($im, $font_size, $x, $y, substr($word, $i, 1), $text_color);
				$x += ($font_size*2);
			}
			else
			{
				$y = rand($img_height/2, $img_height-3);
				imagettftext($im, $font_size, $angle, $x, $y, $text_color, $font_path, substr($word, $i, 1));
				$x += $font_size;
			}
		}
		imagerectangle($im, 0, 0, $img_width-1, $img_height-1, $border_color);
		$img_name = $now.'.jpg';
		ImageJPEG($im, $img_path.$img_name);
		$img = "<img src=\"$img_url$img_name\" width=\"$img_width\" height=\"$img_height\" style=\"border:0;\" alt=\" \" />";
		ImageDestroy($im);
		return array('word' => $word, 'time' => $now, 'image' => $img);
	}
}
?>  